This invention relates to optical systems.
Optical systems are increasingly being used in place of electrical systems for sensing and transmission of data. Such systems may comprise, for example, an optical sensor, a fibre-optic cable and a detector that provides an output representative of the variable sensed by the sensor in accordance with the amplitude of radiation received via the cable. One problem with such analogue systems is that some of their characteristics can drift with changes in temperature and can become especially insensitive at low radiation levels.